1. Field of the Invention
The present invention relates to a novel isononyl acrylate composition composed of acrylates of C.sub.9 alcohols.
2. Description of the Prior Art
Methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate as four typical acrylic esters of alkyl acrylates have been mainly produced in an industrial scale. Homopolymers or copolymers obtained by polymerizing one or more of the ester monomers, if necessary, a comonomer such as vinyl acetate, styrene and methyl methacrylate and a crosslinkable monomer such as 2-hydroxyethyl acrylate, acrylic acid, itaconic acid, acrylamide and glycidyl acrylate, have been used in various fields such as tackifiers, binders, paints, leather treatments, fiber treatments etc.
In the polymerization, an emulsion polymerization, a solution polymerization etc. can be employed.
The homopolymers and copolymers obtained by polymerizing or copolymerizing an alkyl acrylate can usually form soft, elastic films as a characteristic feature and have characteristics of excellent heat resistance, weathering resistance, and oxidation resistance. It has been usually considered by a person skilled in the art to study glasstransition points (Tg) in the productions of copolymers of alkyl acrylate suitable for the object usage. In general, a brittle point of a homopolymer or a copolymer decreases depending upon a decrease of Tg of the homopolymer or the copolymer. Thus, the glasstransition point Tg is used as a standard for softness of the homopolymer or the copolymer. In general, Tg and a brittle point of the homopolymer or the copolymer vary depending upon structures of an alkyl group of an alkyl acrylate. In the case of the straight chain alkyl group, Tg and the brittle point of the polymer decrease depending upon an increase of the number of carbon atoms but increase depending upon an increase of the number of carbon atoms over 8. Thus, it is considered that a homopolymer of n-octyl acrylate (C.sub.8 alkyl group) has highest softness and tackiness at room temperature, among the homopolymers of alkyl acrylates. Among homopolymers of alkyl acrylates having the same number of carbon atoms, the homopolymer of the alkyl acrylate having a straight chain alkyl group has lowest Tg and lowest brittle point. In the case of a branched alkyl group, the homopolymer has higher Tg and higher brittle point than the case of a straight alkyl group. When an alkyl acrylate for lower Tg and lower brittle point is utilized in an industrial scale, the straight chain alcohol as the starting material is expensive and accordingly, the straight chain, alkyl acrylate is expensive. Therefore, 2-ethylhexyl acrylate which gives the lowest Tg among the economical four typical alkyl acrylates, has been mainly used. For example, a homopolymer of vinyl acetate has been mainly used for interior coating in buildings. The homopolymer of vinyl acetate has Tg of 28.degree. C. In order to use it for forming a coated layer, it is necessary to blend a plasticizer. As an external plasticizer, dibutyl phthalate has been mainly used, however, there is found a tendency of migration of the plasticizer on the surface of the coated layer due to aging for a long time. Thus, the physical properties of the polymer in the coated layer are changed by a washing, a wipe-off, and a volatilization to cause phenomena of a deterioration or a bleeding-out. In order to prevent the phenomena, it has been proposed to decrease Tg by an internal plasticizing of the alkyl acrylate. In order to maintain the typical characteristics of the main polymer, it is preferable to reduce the amount of the internal plasticizing monomer. It is advantageous to use the internal plasticizing monomer for lower Tg.
In the productions of pressure-sensitive adhesives, a main monomer for soft and low Tg is admixed with a monomer for hard and high Tg used for improvement of adhesion and cohesion and a cross-linkable monomer or a monomer having a functional group is added and the monomers are copolymerized to obtain the object pressure-sensitive adhesives.
In the productions of paints, the production of acryl emulsions for thick coating paints which are called as elastic paints have been increased for external coating paints for buildings and mansions, because the acryl polymers have excellent weathering resistance, water resistance and durability and the coated layer has excellent elongation to prevent a water leakage accident caused by crackings of the wall. In order to obtain a coated layer having excellent elongation, a main monomer for a soft polymer having low Tg is needed.